Troughton & Simms Theodolite

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This 30-inch theodolite was made by Troughton & Simms in London for the U. S. Coast Survey, probably in the late 1840s. Only the unusually short trunnions, telescope, small vertical circle, and micrometer eyepiece remain. The standards, graduated horizontal circle, and tripod base are missing.
Ref: C. A. Schott, "Determination of the Astronomical Azimuth of a Direction," United States Coast Survey Annual Report (1866), Appendix No. 11.
Currently not on view
date made
late 1840s
Troughton and Simms
place made
United Kingdom: England, London
telescope aperture: 2 3/8 in; 6.0325 cm
telescope: 30 in; 76.2 cm
vertical circle: 5 1/2 in; 13.97 cm
trunions: 12 1/2 in; 31.75 cm
overall: 5 3/4 in x 33 in x 10 in; 14.605 cm x 83.82 cm x 25.4 cm
ID Number
accession number
catalog number
Credit Line
U.S. Coast and Geodetic Survey
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Medicine and Science: Physical Sciences
Measuring & Mapping
Surveying and Geodesy
Data Source
National Museum of American History